250 mL of 0.5 M NaOH was added to 500 mL of 1 M HCl. The number of unreacted HCl molecules in the solution after complete reaction is ___________ $$\times$$ 10²¹. (Nearest integer)

(N_A = 6.022 $$\times$$ 10²³)

The Azimuthal quantum number for the valence electrons of Ga⁺ ion is ___________.

(Atomic number of Ga = 31)

The spin-only magnetic moment value for the complex [Co(CN)₆]^4$$-$$ is __________ BM.

[At. no. of Co = 27]

2SO₂(g) + O₂(g) $$\rightleftharpoons$$ 2SO₃(g)

In an equilibrium mixture, the partial pressures are

P_SO3 = 43 kPa; P_O2 = 530 Pa and P_SO2 = 45 kPa. The equilibrium constant K_P = ___________ $$\times$$ 10^$$-$$2. (Nearest integer)